Aegis
by Byronic Heroine
Summary: Yukio always takes it upon himself to protect Rin.  The older Okumura twin takes it upon himself to convince him otherwise through rather unconventional means.  OKUMURACEST


**Author's Notes**: I can proudly say that I've become a rabid Blue Exorcist fangirl in the last couple of months. More specifically, I've become a rabid supporter of Rin x Yukio twincest... the result being this here fic, which happens to be my first real attempt at a smut fic. When I say real, I mean it is neither (a) given up on halfway through or (b) a finished but cringe-worthy effort that is both anatomically incorrect and painfully cliche, which is what I found when looking back at stuff I'd written around a year ago... stuff that will NEVER be posted here, EVER. However, I can confidently say that my skills have considerably improved since then! So... here be smut, folks. There _is_ some plot, but c'mon, who cares about _that_? XD

This takes place around episode 17 of the anime, in the weeks after Rin's battle with Amaimon in the forest and his subsequent hearing with the Vatican. Yukio is stressed out on Rin's behalf, worried that his older brother will do something stupid that will endanger his life again and get him in trouble with the exorcist authorities. That's the premise that this fic is based on.

Warnings: Boys being boys (what did you expect?) and, um... tail play?

Enjoy!

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><p>Yukio walked into their dorm room to find that Rin was, of all things, reading manga next to a pile of textbooks that the younger twin knew hadn't even been opened.<p>

In a time like _this_. In a situation as delicate as _this_.

It was enough to make his blood boil.

"Rin, what are you doing?" he asked in a dangerously quiet voice.

Rin either didn't notice the uneasy edge in Yukio's tone, or didn't care. He flashed his twin a carefree grin and replied, "Catching up on my favorite series! I haven't read it in a while, and now it's finally starting to get really intense…" He returned his attention to the tankobon volume he was holding and hummed an ambiguous tune, his tail playfully flicking back and forth.

"Isn't there something else you could be doing?" Yukio asked coolly. "_Studying_, maybe?"

Rin did look at him then, really looked, and saw that twitch in his brother's brow that he'd long ago learned to associate with an icy-hot anger that was just barely being contained.

"Jeez, calm down, would you?" he said casually. "What're you so pissed for?"

Yukio tensed, his hand clenching into fists at his sides, and barked a humorless laugh. "Oh, not _pissed_. I'm merely… _disappointed_."

Rin raised a mildly concerned eyebrow. Yukio's suddenly odd behavior _was_ a bit unsettling. "Disappointed?" he parroted.

Yukio's glasses flashed ominously as he replied, "Yes, disappointed. That, despite everything that's happened, the Vatican have given you a second chance… and you're throwing it away. Throwing you _life_ away." He allowed some of the rage that he struggled to smother underneath a cold demeanor creep to the surface as he spoke.

Rin held his hands up in a sudden defensive gesture. "Whoa, okay… throwing my life away? That's a bit much. Don't get all melodramatic on me…"

His brother just wasn't _getting_ it, and it infuriated Yukio to no end. As usual, Rin was making a big joke out of a grave situation, not caring about what was at stake. Not caring that it was his _life_ that was at stake.

It drove Yukio over the edge, and the rage he'd managed to thus far keep restrained exploded forth in a venomous deluge.

"You could have _died_, Rin! When you went berserk in that forest, Angel was ready to kill you right then and there. Him and the rest of the Vatican. They don't know the human side of you, all they see is a monster, a threat that has to be eliminated. You would have been put to death if Pheles hadn't pleaded your case! So now, despite the disgust they feel towards your very existence, the Vatican have allowed you to stay alive, under the very reasonable conditions that you continue your training and successfully attain your next rank as an exorcist… and you're not even _trying_ to act like you're putting in any effort! Are you even aware of how precarious your position is? Your _life's_ on the line, and you're acting like you don't even _care_..."

"Yukio." Rin interrupted him, in a voice that was serious, pensive. Yukio hoped against hope that maybe he'd actually managed to get through that thick skull of his.

A hope that was promptly dashed into pieces against the wall as Rin finished, "Would you just shut the hell up?"

Yukio felt like some unseen force had just slammed into him and squeezed all the air from his lungs, leaving him with an incoherent cry of outrage that just barely managed to escape his throat. He stood staring at Rin with his mouth half-open in disbelief, unable to speak.

Rin yawned and stood up, his tail lazily sweeping about his ankles. "I'm gonna get some mineral water, 'kay?" He began to walk towards the door. "If you want one too – "

"Oh, no you don't," Yukio hissed, refusing to let Rin escape now. His hand darted forward faster than his twin's eyes could follow, and clamped onto the first thing he could reach… which happened to be Rin's tail.

Rin screeched like he'd just been thoroughly violated. "Dammit, Yukio, let go!"

"I'm not letting you go until you listen to what I have to say."

"Yukio, I mean it… let _go_ of me." Rin attempted to wriggle out of Yukio's grip; Yukio pulled him back towards him, yanking his tail harshly.

"Shit, that _hurts_!" Rin yowled. "What the hell is wrong with you?"

"What's wrong with _you_?" Yukio shouted, pleased to see Rin actually flinch at the sudden increase in volume. "The life that you're tossing around so carelessly is the one that Dad died for! To carry on as you have been, acting so recklessly, is an insult to his memory. If you actually cared about him…"

Rin smacked him across the face. Yukio watched his glasses land in a far corner of the room, and knew from the sound of tinkling glass that they'd been broken. When he turned back to his brother, it was to find him surrounded by demonic blue flames, his pupils flashing red. "Don't…you _dare_…suggest that I didn't love him. _Ever_."

"Then start acting like you did," Yukio retorted, not daunted in the least by Rin's transformation, intoxicated now with the desire to see his brother pushed to breaking point. "You could start by not flaunting those flames every time you don't get your way. Maybe if you'd been able to control them back in the forest, your so-called friends might actually want to be associated with you instead of being repulsed by your existence – "

Rin bared his sharpened canines and roared, lunging for Yukio with no thought in his rage-clouded mind other than the need to inflict pain, pain, _pain_.

They crashed to the floor in a violent tangle of limbs, abandoning any and all restraint. Rin clawed at Yukio's body and Yukio kneed him in the stomach; they punched and kicked and grappled in a savage yet strangely intimate embrace, arms and legs intertwining in the chaos, bodies pressed close enough that one could feel the heat roiling off the other.

It ended as abruptly as it had begun, in what could only be called a stalemate: Rin held his twin captive beneath him on the floor, legs splayed on either side of Yukio's body and hands pinning down his shoulders; Yukio held Rin's ever-suffering tail firmly in his hand.

The sapphire flames licking at Rin's body shrank, and then disappeared completely. Azure eyes met turquoise, and the two boys remained silent save for the sounds of their ragged breathing.

Rin was not the only one who came back to his senses then. Yukio had no hellish flames of insanity to speak of, but he'd been just as guilty as Rin for causing this fight, if not more. Drunk as he was on the power that he'd held over his brother's emotions, he'd lost sight of his original intentions. He'd wanted to talk to Rin, have a serious conversation with him, and that matter still needed to be taken care of. He notice with some embarrassment that another, new matter of an entirely different nature was requiring his attention now, as well… but, all in due time.

"Nii-san, he said, with none of the earlier fury that had manifested itself through impassioned wrestling and clawing.

As soon as Rin heard his twin speak, he broke their gaze and focused on a vague spot beyond Yukio's shoulder.

"Nii-san," Yukio said again, almost pleading. "Look at me."

After a moment of hesitation, Rin reluctantly complied.

Yukio finally stated what had been on his mind from the beginning. What had initially been cruel, scathing accusations and barbed insults now came out candid and simple: "I just want to protect you."

Rin sighed, familiar at this point with this particular spiel. "For crap's sake, Yukio… not this again." He made to get off of his brother, but Yukio held him down by the tail, not harshly like last time, but firmly enough to elicit a growl of discomfort.

A growl of discomfort with a detectable undercurrent of something else.

Interesting, Yukio thought.

Not releasing his grip on Rin's tail, Yukio said gently, "I swore I'd protect you with everything I had. I made a promise to Dad. I have to honor that promise. You understand that, don't you?" His hand drifted up and down the length of Rin's tail, teasing the short fur, and tugged again. Rin groaned, affirming Yukio's suspicions – underneath the assertion of pain was the undeniable stain of arousal.

"Yeah, I… get it," Rin squeezed out through gritted teeth. "But you don't have to be so… _ah_…" Yukio's hand had wandered to the end of his tail, toying with the tuft of long fur there, his thumb applying pressure to the tip and rubbing in small circles.

"I need to protect you, Nii-san. That's a promise I have to keep. But there's a selfish reason as well." He kept his softened eyes riveted on his twin's darkening ones as his hand continued to stroke softly, watching in affectionate amusement as his eternally proud Rin struggled to stay silent.

He reached upward with his free hand and laced his fingers through messy black hair, pulling Rin's head down towards him. "A selfish reason that eats away at my thoughts: if I ever lost you, who would I have left?"

He closed the distance between them with a tentative, chaste kiss that was over far too soon. When they broke apart, Rin flashed him one of those wide, toothy grins that could always fill Yukio with the warm reassurance that everything would be all right. "Idiot," Rin said, "How the hell is that selfish? You may be really smart, but sometimes your logic makes no sense." Their lips met once more, this time with a bit more urgency. Rin's quiet moan broke into Yukio's mouth as the younger continued to fondle his tail, threading it between his fingers. Yukio took advantage of the moment to push his tongue further into Rin's mouth, coaxing him to deepen the kiss. He could feel Rin's hands tremble as they pressed against his shoulders, fisting his jacket in an effort to stay rooted to _something_, to not completely lose himself. Yukio knew then that it was time to drive his brother over the edge.

He abruptly pulled away from the kiss, a silver thread of saliva trailing between their mouths before delicately breaking. He readjusted his grip on Rin's tail and _squeezed_ until Rin released a broken gasp of something on the fragile line between pain and pleasure; then he brought it up to his lips and pressed a teasing kiss to the tip, causing Rin's hips to shudder involuntarily, as Yukio knew they would. His hand ghosted over Rin's clothed erection, earning another surprised gasp from the half-demon, and he asked mirthfully, "When did you get hard? Was it when I started playing with your tail? I know it's your weak spot. Or was it even before then? Maybe it was when we were wrestling so… intimately?"

"Hypocrite," Rin shot back. "Don't try to act like you weren't affected by that, too." He placed one of his legs between Yukio's and dug his knee into Yukio's crotch, locating the telltale hardness with some degree of triumph.

Yukio couldn't help it – the sudden contact drew a tremulous whimper out from between his lips, and he looked up to find Rin not even bothering to suppress the smirk that had crept onto his face.

The fact that his brother was not completely impervious to the effects of arousal inspired Rin with a notion that he toyed with for a few moments before voicing it aloud. He pressed his knee against Yukio's dampening crotch once more, watching in satisfaction how it made him shudder, and suggested, "You're always working so _hard_, Yukio. Why don't you sit back and let me take over for once, hmm?" He bowed his head and bit down gently on Yukio's ear, poking at it curiously with his tongue.

Yukio shivered at the low, seductive quality that his twin's voice had taken, and found that he was powerless to resist. "All right," he conceded, and then, so he wouldn't seem like a total pushover, added, "But you had better make it good."

Warm breath tickled his ear as Rin chuckled. "I'll try my best, _brother_," he said, accentuating the last word with a measured thrust of his hips.

Both of them gasped at the welcome friction that provided their respective erections with much-needed attention. It took a ridiculous amount of restraint for Rin not to do it again; no, he wanted to make this last, and figured that a bit of teasing wouldn't hurt.

He extricated his hands from his twin's shoulders and sat back on Yukio's thighs, allowing him to finally sit up straight instead of being pinned directly underneath Rin. He pressed his lips against Yukio's in gasping, searching kisses, pausing in between hurried breaths only to growl fragments of a command: "Against the wall… more leverage that way…"

Yukio edged backwards until his back met the wall and found that its hard, unyielding surface did provide more leverage and comfort, allowing him something to lean against. Rin wasted no time in resuming his thorough ministrations; his lips found the crook of Yukio's neck and he nipped teasingly at the tender skin there, knowing that focusing on that place especially wound garner a response. Sure enough, Yukio virtually thrashed against him, releasing a string of uncharacteristic mewls and whimpers. Rin traced a delicate blue vein near Yukio's throat, and then impishly bit down, delighting in the yelp of surprise that ensued. He kept his mouth firmly attached to the spot and sucked gently, reducing Yukio to a shivering mess as his hands scrabbled at Rin's shoulder blades, desperately searching for purchase.

"Rin… nngh… are you _trying_ to drive me insane?" Yukio gasped.

His older brother grinned wickedly against his neck. "Just a little." Deft fingers undid the buttons of Yukio's jacket with unexpected skill, sliding it off of his shoulders before setting to work on his shirt. Rin trailed an errant forefinger lightly down the pale strip of finely muscled torso that was now exposed, breathing in sharply in appreciation. Over-sensitized as he was to every caress, Yukio found this absolutely maddening.

"Nii-san!" he nearly shouted. "Just get… _ah_… just get on with it already!"

"Ask nicely," Rin murmured as he nibbled on his collarbone.

Yukio groaned; Rin could be such a _kid_ sometimes. "All right, fine," he panted. "Please. _Please_ get on with it."

"Say that you'll stop trying to protect me all the time."

Yukio abruptly stopped his struggle and met Rin's eyes steadfastly. Rin realized as soon as the words were out of his mouth that he'd crossed over some sort of line.

Yukio, after a pregnant pause, responded solemnly, "You know I can't do that."

Rin bit his lip, seeing the resilience behind Yukio's eyes and knowing that it was sincere. Yukio was no longer the weak twin, no longer that soft-spoken, sensitive little boy who depended on his older brother to defend him. He's grown so strong, had surpassed his twin in so many ways. It filled Rin with a warm swell of pride; however, that pride was interwoven with the lonely sadness that comes with the awareness that an irreversible change has taken place, for better or for worse, in one's beloved. A tinge of trepidation, fear even, prickled inside of him as well – fear that Yukio had become so strong that he no longer needed a brother to lean against.

He realized with a start that his fear and Yukio's were one and the same.

Yukio mistook his twin's silence for antipathy, and hastened to try to put the maelstrom of emotions tearing through him into words. "It's just that… I mean, I… I want to…" For once, the genius exorcist prodigy was at a loss for words.

He felt a slender finger press against his lips, and his eyes found electric blue ones that glinted with amusement and something else… empathy.

"I know it's hard to explain, so don't even try," his older brother murmured. "But… I think I understand." One hand cupped his cheek, thumb absently drawing imaginary lines on his skin.

There was one frightening moment where Yukio felt that he might just break down and sob with relief, but he swiftly shoved the urge aside – he knew Rin would never let him hear the end of it if he did something that ridiculous. So he settled instead for simply placing his hand over the one that already rested on his cheek, radiating warmth.

"Thank you, Nii-san," he whispered, before he closed his eyes and succumbed to the feel of Rin's lip pressing against his with surprising tenderness.

Yukio loved that, even though they'd known each other's bodies since birth, Rin could still make him feel like he was exploring his body for the first time. The way he was touching him now… his hands, so hot they almost burned, slid from Yukio's face onto his shoulders, fingertips tracing his throat and the smooth edge of his clavicle. From there they drifted to his exposed chest, where they could no doubt perceive his erratic heartbeat. One thumb began to massage an erect nipple; Yukio gasped and arched into the touch, his erection straining against his pants to the point of being almost painful. Rin was kissing him deeply now, lips undulating passionately against his own. Rin's tongue was just as demanding as the rest of him; it seized possession of Yukio's mouth without warning, thrusting past his parted lips with the intention of tasting as much of Yukio as possible. His teeth occasionally joined the fray as well, nipping and tugging at his lower lip. Rin's hands were relentless in their exploration; one continued to rub Yukio's nipple, pinching it between thumb and forefinger, while the other roamed anywhere it had missed. He trailed his fingers down the middle of Yukio's torso, gliding over his navel, and then slid his arm behind him, running his hand teasingly over the curve of his ass before settling it on the small of his back. He purposely skipped over the obvious tent in Yukio's pants, which his twin was painfully aware of.

"Nii-san…" Yukio groaned, past the point of caring about how needy he sounded. He wanted this, he wanted Rin, and Rin was taking full advantage of his control to proceed maddeningly slowly, stretching his brother thin enough to snap.

His pleading tone must have triggered something within his twin, because a flurry of movement immediately followed after he spoke. Rin's hands found Yukio's, and he pressed their palms together, fingers intertwined; the next thing Yukio knew Rin was pinning both of his hands against the wall, immobilizing him rather effectively. Rin swung a leg over one of Yukio's thighs, and Yukio suddenly found himself being straddled full-on: Rin's legs were splayed on either side of him, his bottom finding its way onto his lap. But the most prominent detail was the fact that this position allowed their erections to be pressed flush against each other. Yukio released a very un-Yukio-like squeak, which his brother would have laughed at had he not emitted an embarrassing, high-pitched mewl just moments before.

Rin thrust forward experimentally and shivered as sparks of pleasure crackled down his spine. He tightened his hold on Yukio's hands and began to rock his hips as he straddled him, forcing himself to start at a leisurely pace.

Despite the onslaught of feeling that threatened to make his other, already dulling senses shut down completely, Yukio managed to gasp, "Nii-san, shouldn't we… _nngh_… take off our pants, at least?"

"No…" Rin mumbled against his neck. "Through our clothes…"

And, considering that what they were doing felt too good to even think about stopping for something as trivial as clothing, Yukio really couldn't complain.

As Rin's pace slowly escalated, Yukio arched his lower body upward to meet his thrusts. Every motion sent a jolt of intoxicating pleasure coursing through his veins, manifesting itself verbally in uncontrollable whimpers and moans.

When his younger brother began to reciprocate his movements and make those sounds, it was almost enough to make Rin lose it right then and there. It was only by slowing down his pace significantly that he was able to hold off his impending orgasm. Yukio noticed the change and deduced what it must have been attributed to with a twinge of amusement. He was tempted to make some sort of crack about his older brother's stamina; however, any form of coherent thought was vaporized as Rin claimed his mouth in another demanding kiss, licking and biting at his lips, sucking on his tongue. Yukio released another trembling moan, overwhelmed by the influx of sensation that his body was trying to process all at once. The feel of Rin's tongue repeatedly penetrating him coupled with the heated friction against his erection was a staggeringly heady mixture, one that continued to cloud his already hazy senses. Rin began to speed up the rocking of his hips, losing himself in the rhythmic, almost hypnotic pulses of pleasure that churned through his core and pooled at his groin. He stopped kissing Yukio and pulled away, so that he could really, truly watch him; watch the way his eyelids fluttered every time his twin ground against him; the flush of pink dusting his cheeks; the way his lips parted so delicately, just enough to release one of those little mewls that was so tantalizingly erotic. This was his Yukio, and the state that he was in was all Rin's doing; that thought alone was enough to make him move even faster, dizzy with the force of his arousal. He muffled his shuddering gasps against the crook of his brother's neck as his hips bucked more and more violently, seemingly of their own accord.

His orgasm hit with the force of a tidal wave, and rode it out for as long as he could, grinding erratically against his twin as ecstasy whited out his vision and took control of his body. There was a pure, perfect moment where all he felt was the utter bliss of his climax and has brother's hands holding tightly onto his own; and then it dissipated and was gone, leaving him slumped against Yukio's shoulders, still straddling him. After regaining his composure enough to speak, his eyes found Yukio's and he murmured, "You didn't come yet, did you?"

Yukio bit his lip and flushed an even deeper shade of red. "Well, no, but… it's okay, I… _ah_…" Rin's hand was at his crotch, palming him through the fabric of his pants. He stroked Yukio's still-hard length with vigorous determination, pumping at an almost ungodly pace; Yukio dispelled the last of his inhibitions and vocalized every wave of pleasure that rippled through him in breathless cries and moans.

It wasn't long before he, too, ascending into the rapturous throes of release. His mouth opened in a wordless scream as he thrust into Rin's palm and clung to his body, delirious with euphoria.

When he finally climbed down from the heights of his climax, he sat back against the wall, still breathing heavily, and allowed Rin to collapse against him. They laid like that for a long time, completely unmoving save for the rise and fall of their chests: Rin sitting in Yukio's lap, head resting on his brother's shoulder, while Yukio's arms had crept around him and pressed his body snugly against his torso. The admittedly uncomfortable wetness down below could wait; Rin would gladly have stayed frozen there forever, held tightly in his brother's arms.

As it was, instead he tilted up his chin and pressed an affectionate kiss on his lips. "Yukio," he said gently, and their gazes connected.

"Yes, Nii-san?"

Rin broke into another one of his trademark grins and said, "You gotta let me do some protecting too, okay? Remember when we were kids? How many times I saved your ass?"

Yukio chuckled at his twin's earnestness. "Yes, I remember."

"Well, I can still do that, you know. You take it upon yourself to take care of the both of us, but I can do that too. I love you, Yukio… so I want to be _your_ protector sometimes." He beamed proudly. "I've got your back. I'm your big brother, after all!"

Yukio tensed slightly at his words then, his fingers digging into Rin's waist unintentionally. Rin winced at the pain but said nothing. He knew that what Yukio was undergoing right now was very difficult for him, and it was something that he needed to do without any further interference on Rin's part. So the older twin simply kept silent and decided to wait for however long it took for Yukio to reply.

When Yukio looked at Rin he saw many things: the impish young boy from his memories who, despite his delinquent attitude, watched over him fiercely; the reckless young man he was now, who charged into battle without second thought and still had so much to learn; and the incredibly strong individual that he could – no, would – someday become. The images would always conflict with one another, making Yukio unbearably confused as to what Rin truly was. But now, finally, he had a sudden instant of clarity, in which he realized that the seemingly incongruous views that he had of his twin really weren't incongruous at all. The conceptions didn't conflict with each other; they complemented each other, and that made all the difference. No one was made of steel; every person had to go through his or her trials and weak moments. It was how they emerged from them that really determined their strength. And Yukio knew, with the unconditional trust of a younger brother looking up lovingly to the older one, that Rin would emerge victorious from his struggle and be the dearest protector he could ever hope for.

When he was younger, Yukio would always feel a pang of sadness when he saw Rin defending him, him and his weakness. It was when his brother protected him that he felt the most distant from him, because he knew that he could never hope to catch up to him. That pang resurfaced now, making doubt and indecision flare up in his chest, as he realized how strong Rin would become.

But, after wrestling with the feeling for a single, uncertain moment, he succeeded in banishing it for what he hoped to be forever. He resolved that, even if Rin surpassed him once again, he would always be just one step behind him.

_I'm your big brother, after all!_

As the words echoed through his head, Yukio smiled. "You're right, Nii-san. I forget that too often, I think." He readjusted his grip on his twin's warm, comforting body, hugging him closer.

Content with the knowledge that his twin was finally at peace, Rin allowed Yukio to hold him as close as he possibly could.


End file.
